Cutting and cooling lubricant



Patented Jul 11,1939

CUTTING AND ooonmc LUBRICANT John C. Zimmer, Hillside,and John B. Holtaclaw,

Roselle, N. J.-, assignors to Standard Oil Development Company, a corporation of Delaware No Drawing.

Application August 19, 1936,

Serial No. 96,812

4 Claims. (CI. 87-9) This invention relates to an improved lubricating composition and more particularly to compositions adapted for lubrication and cooling of surfaces operated at high speeds and pressures, such as are used in metal cuttingoperations.

In the past, water'solutions or emulsions of soluble cutting oils prepared from sulfonate soaps and the so-called sulfo-naphthenates extracted from petroleum sludge have beenused extensively in the metal fabricating industry for the lubrication and cooling of metal cutting tools in slow speed turning, drilling, grinding and similar operations on malleable and other soft irons and steel, primarily for cooling or heat dissipation. High speed cutting, however, demands more oily lubricants to prevent chattering, welding of the tool to the work and to prolong tool life to a reasonable period. These aqueous emulsions have not proven satisfactory in such high speed operation, particularly on tough alloy steels, and the metal industry has used almost universally in the It has now been found that higher production .--speed, longer tool life and a better finish on the work can be obtained in metal working, particularly in high speed operations on tough alloy steels, byusing an improved lubricating .composition comprising an aqueous emulsion of an extreme pressure lubricant or cutting oil such as a sulfurized fatty oil. By this means the high film strength and high lubricity or oiliness of .the sulfurize'd oils is combined with the heat absorbing properties of aqueousemulsions in the form of a stable emulsion which is non-corrosive to steel even at elevated temperatures and which possesses -extreme pressure lubrication and high film strength properties'equal even to the best commercial straight sulfurized cutting oils.

, Stable emulsions having these properties are secured even when the composition of the present invention is diluted with from to 20 parts of water to one part of the lubricant base.

The composition of the present invention contains about 50 to' 90% of a mineral oil, preferably a petroleum lubricating oil having a viscosity below about 500 seconds Saybolt Universal at 100 F.', although more viscous oils can be used. It also contains a suitable proportion of a sulfurized fatty oil to impart the desired high film strength characteristics' The amount of this sulfurized fatty oil may vary widely depending upon the operating conditions to which 'the'composition'is' to be subjected and-a concentration between purposes. The preferred concentration is about 5 to The sulfurized oil may be prepared by any-suitable method in use for introducing sulfurinto the organic molecule in a form imparting extreme pressure lubrication characteristics thereto. One

' suitable method is to heat a mixture of the lard oil with preferably from 10 to of flowers of sulfur, with stirring, to a temperature of about 350 to-450" F. The sulfurized oil preferably contains about 5 to by weight of sulfur. It is the sulfurized lard oil, such as the fatty oils of vegetable, animaland marine origin, also the fatty acids derivable from such oils, and the acids of similar molecular weight obtained by the limited oxidation of parafiin wax at low temperatures. The composition also contains a suitable proportion of an emulsifying agent to render it readily miscible or emulsifiable with water. Any suitable agent for preparing emulsions of oil and Water may be used which is not objectionably corrosive to metal surfaces. Examples of such emulsifying agents are the mahogany soaps derived from the treatment of petroleum'oils with strong or fuming sulfuric acid, naphthenic acid soaps such as those derived from petroleum crudes containing naphthenic acids, sulfonaphthenic acids, such as those obtained by the treatment of naphthenic base oils" with strong or fuming sulfuric acid followed by the recovery from the oil of the resulting mixture of organic acids, also the ordinary fatty oil soaps of fatty acids with suitable metals, preferably ammonium and the alkali metals sodium and potassium, and also similar soaps of wax acids, i. e., acids obtained by the limited oxidation of paraflin wax at lowto 3% will be found suflicient.

The composition may also contain a small amount of rosin soaps which may be added in proportion of about 1 to 10%.

, The composition is preferably slightly alkaline and may be made so by adding asmall amount Such of any strong alkali such as sodium or potasg sium hydroxide, soda ash or carbonates. Generally a fraction of 1% of the alkali is suflicient. A small amount of water, from about to 3%, may be used and aids in carrying the alkali into the solution.

Example I The following example is presented in order to illustrate a suitable embodiment of this invention but is not intended to limit this invention in any way:

Percent Mineral oil-100 seconds Saybolt viscosity at 100 F 59.1 Sulfurized lard oil 10.0 Mahogany soap 22.0 Diethylene glycol 2.0 Rosin 4.3 Caustic soda 0.6 Water 2.0

In the above example the mahogany soaps consist of a solution by volume of-oil soluble sodium sulfonates-in oil, which is preferably a mineral lubricating oil of about to 500 seconds I Saybolt Universal viscosity at 100 F.

The above composition, 'when diluted with 16 volumes of water to one volume of this composition carries the full load of 15,000 pounds per square inch on the'Almen machine, using steel to steel bearings, with a maximum friction of 30 pounds inches. Similar compositions containing ordinary (unsulfurized) lard oil, carry only 3,000 to 6,000 pounds per square inch in this test.

Example II The following tests were conducted to compare the efiectiveness of this composition with emulsions of non-sulfurized cutting oils. Closely comparative tests were made in cutting a stand- ,ard steel, and tool life was measured at several different cutting speeds. The results are presented in the table below.

Lubricant A is an emulsion, in ten parts of water, of one part of the composition described in Example I. Lubricant B is an emulsion, in ten partsof water, of.one part of the same composition, omitting the sulfurized lard oil and diethylene glycol.

In these tests, the applicants composition (A) gave entirely satisfactory operation and showed no tendency to corrode or rust the metal surfaces. Tool lives 50 to 100% greater than those with the sample B were obtained. In contrast with-these results, emulsions prepared from sulfurized mineral oil or sulfurized sulfonates severely corrode steel even at ordinary temperatures within a few hours. I 7

While straight, or water-free, cutting oil compositions possess some advantages over sample B, they are much more expensive than the applicants" composition and are greatly inferior as cooling agents. accordingly permits rapid cutting at lower temperatures and safer and more accurate work.

This invention is not to be limited by any specific examples or explanations presented herein, all of which are intended solely for purpose of illustration, but is to be limited only by the following claims, in which it is desired to claim all novelty insofar as the prior art permits.

We claim:

1. An alkaline oleaginous composition suitable for emulsification with water to form a cutting and cooling composition comprising about 50 to about of a mineral lubricating oil, about l to about 20% of a sulfurized fatty oil, about to about 3% of a glycol ether, about to about 3% of water, about 1 to about 30% of mahogany soaps, about /2 to about 10% of rosin and containing, also, about 0.6% of a strong alkali.

2. A cutting and cooling oil composition comprising an emulsion with about 10 to about 20 volumes to water of one volume of an alkaline mixture containing about 80% of a mineral lubricating oil, about 20% of a water-soluble soap as an emulsifying agent, about 10% of a sulfurized fatty oil, about 5% of rosin, about to about 3% of a glycol ether and about 0.6% of a strong alkali.

3. An alkaline oleaginous base emulsifiable The use of applicants emulsion with alkali to form a cutting and cooling composition comprising about 81% of a mineral lubricating 011, about 22% of mahogany soaps, about 10% of sulfurized lard oil, about'4.3% of rosin,

F., 10% of a sulfurized lard oil, 22% of a mahogany soap, 2% of diethylene glycol, 4.3% of rosin, 0.6% of caustic soda and 2.0% of water.

JOHN C.ZI1VHVIER. I JOHN B. HOLTZCLAW.

'oil having seconds Saybolt viscosity at 100 

